Conventionally, in the technical field of vehicle lights various semiconductor light emitting devices have been utilized, as disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2005-322923, 2008-507805 and the like. Such semiconductor light emitting devices can have a light emitting diode chip and a wavelength conversion layer formed on the surface of the light emitting diode chip with a uniform thickness. FIGS. 1 and 2 show one example of a conventional semiconductor light emitting device having a light emitting diode chip Cp and a wavelength conversion layer Ly formed on the surface of the chip with a substantially uniform thickness. As the semiconductor light emitting device described in Japanese Patent Application Laid-Open No. 2005-322923 has the wavelength conversion layer with a uniform thickness, the luminance distribution thereof takes its maximum value at and near the chip center (around its optical axis) and gradually reduced values toward the periphery thereof (see FIG. 3). This is a similar phenomenon to the Lambertian distribution for surface light emission, and can be explained as a phenomenon in accordance with the COS function wherein, if in-plane luminance distribution is uniform, the center area shows the maximum value.
In the technical field of, in particular, vehicle headlights, the maximum value in the luminance distribution of a vehicle headlight is required to be arranged at or near the cutoff line in order to form a clear cutoff line. To comply with this requirement, a shade or the like shielding member must be utilized to cut the half of the luminance distribution as shown in FIG. 4. When the configuration including such a shade is employed, the light at the maximum value in the luminance distribution cannot be utilized, thereby reducing the light utilization efficiency.